The headset is the last part of a bike to be tackled in my self-education. I have built many bikes, converted some, but the frame always had a pre-installed headset. Having built a solid headset press out of allthread, washers and nuts, I set out to press the cups into the headtube. And then, trouble.

A 1 1/8" threadless setup quickly turned into a...mystery. I thought it was as simple as matching steerer tube diameter, but when testing the cups in the head tube, I discovered they are too small by a significant margin. I measured the inside diameter of the headtube and came out at 1 5/8" - half an inch in difference. The headtube on the 2007 GT Legato frame looks just like all of my other 1 1/8" bikes, so I am obviously missing something. All of the parts for the headset are accounted for, but since the cups are so much smaller, there's nothing to 'press': It just sort of sits in the headtube looking stupid, like the person installing it.

I know there are standard, integrated and 'Aheadsets', so I'm off to read what I can find, but I am not finding what I need on the Googlenet. Any help from this crowd would be much appreciated.

You undoubtedly have one flavor or another of an "integrated" headsets and, unfotunately, there are a lot of incompatible "standards". A Google search on your bike came up with a BikePedia listing saying it has a "1 1/8" threadless TH Intellaset" headset so that is one form of integrated. TH Indistries makes most, if not all, of FSA's headsets so I assume it uses one of their configurations.

I recommend you take the frame to a competent LBS and try to match it with the correct headset. If it is really an integrated headset, you won't need your cup press, just a crown race setter, and possibly not even that. Some FSA headsets come with "split" crown races that install with just finger pressure.

Thanks. I am learning now about the SHIS part of the equation. The headtube is straight bore, no taper. I guess my best bet is to take it to the LBS. From what I have read, Integrated wears faster than a typical headset. Just want to have a place to securely place my steerer tube.

If there are no flared bearing seats at each end of the headtube I don't know what to make of it. Are you certain you bought a 1-1/8" headset, not a 1" headset? A 1" headset would be obviously too small to press into a 1-1/8" headtube.

That's not correct. The sealed bearings in an integrated headset last every bit as long as those in a "conventional" headset and are replaced just as easily. Also, any wear occurs to the bearings themselves, not to their cups or the recesses in the frame.

Since it's a straight bore we can rule out an integrated headset.

It's possible that your bike used reducer inserts at both ends of the head tube, or possibly took a 1-1/2" headset of the type used on DH bikes. Refer to Sheldon Brown's cribsheet here and see if any possibilities make sense to you.

It is one of the Nashbar GT Legato frames.

From chrisking.com re: integrated headsets.

Live and learn. It is a basic frame, so I'm sure nothing fancy, but will check at the LBS.

The answer turned out to be: The FSA Intelliset. There is no alternative, and at $60 a pop, not going to sink that money into it. Frames going back to Nashbar.